Stardust Browser Extension

Stardust shows the cost, electricity, carbon and water behind AI chats on ChatGPT, Claude and Gemini.

Free and open source (Apache-2.0) · Code on GitHub ↗

The Stardust popup open on claude.ai after a reply. The last reply has indicator code C4-M, with model, estimated tokens in and out, cost $0.07, electricity 0.800 Wh, 0.294 g CO₂e, 3.95 mL water, energy source and confidence. Below is a running total for 41 measured operations.
The Stardust popup after a reply on Claude. Browser figures are estimates.
How It Works

Private by design, one site at a time

1

Opt in per site

Stardust measures nothing until you turn it on, and you turn it on separately for ChatGPT, Claude and Gemini. Switch any site off at any time.

2

Counts, never content

Only character counts and the model name are sent, never the text of your messages or replies. No account, name or email: each install gets an anonymous ID.

3

An A–F code for every reply

Each reply gets an indicator code, from A (lightest) to F (heaviest), with a breakdown of estimated cost, electricity, carbon emissions and water, plus a running total.

Chat sites don't show token counts, so browser figures are estimates and are labeled as such. The methodology and factors are public and versioned in the Stardust repository.

Open Source

Free, open source, and built by a nonprofit

Stardust is free and open source under the Apache-2.0 license. It's built by AI for Ecology (AIforE), a 501(c)(3) nonprofit working on standard, transparent measurement of AI's environmental footprint. The extension is one part of Project Stardust, AIforE's open AI sustainability operating system.

GitHub repository ↗ Privacy policy Support & issues ↗